Method of treating light-metal alloys



UNITED STATES PATENT OFFICE.

WILLIAM B. "VIli-AZ'EY, 0F CLEVELAND, OHIO, ASSIGNOB TO THE DOW CHEMICALCOMPANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN.

METHOD OF TREATING LIGHT-METAL ALLOYS.

No Drawing.

Toall whom it may concern.

Be it known that I, WILLIAM R. VEAZEY, a citizen of the United States,and a. resident of Cleveland, county of Cuyahoga, and State of Ohio,have invented a new and useful Improvement in Methods of TreatingLight-Metal Alloys, of which the following is a specification, theprinciple of the invention being herein explained and the best mode inwhich I have contemplated applying that principle, so as to distinguishit from other inventions.

The present invention, relating, as indicated, to the treatment of lightmetal alloys, has more particular regard to the treatment of alloyswhich consist principally, or entirely, of magnesium and aluminum,wherein such magnesium is the predominant metal. It is known that alloysof magnesium and aluminum, wherein such first mentioned metalconstitutes 80 per cent. and upward of the total, possess valuablecharac teristics when in the form of cast articles, but, so far as I amaware, it has never been heretofore found practical to forge orotherwise similarly work an alloy of this constitution. I have nowdiscovered, however, that by bringing such an alloy to a propertemperature before thus forging or similarly working the same, itstensile strength may be greatly increased and other desirable qualitiesimparted thereto.

aving regard to the accomplishment of the foregoing and related ends,the invention, then, consists of the steps hereinafter fully describedand particularly pointed out in the claims, the following descriptionsetting forth but one of the several ways in which the principle of theinvention may be used.

As previously indicated, the present improved method relatesparticularly to the working of magnesium-aluminum alloys, wherein thefirst mentioned metal largely predominates. As a specific example of analloy of this type, which has been found eminently satisfactory forcastings, the following composition may be given, viz. 91.5 per cent. ofmagnesium and 8.5 per cent. of aluminum. This alloy cannot be forged atall in the cold, althou h it readily lends itself to ordinary macfiineoperations, such as turning, boring and pohshing. In endeavoring to find8,. temperature at which Specification of Letters Patent.

Application filed January 21, 1920.- Serial No. 353.097.

such alloy may be successfully forged, I have discovered that even atemperature as high as 450 F. is too low, the alloy shattering likeglass, while at temperatures much in excess of 800 F and thence upwardlyto the point of fusion of the alloy, any attempt to forge or similarlyhandle the alloy likewise results in shattering the same into granularform, much as sugar cake would be crushed by hammer blows.

I have discovered, in other words, that for satisfactorily working analloy of the particular composition cited above, either between swagesor in forging dies, the alloy should be raised to a temperature ofapproximately 600 F.,' and preferably such swages or dies should bemaintained at ap proximately the same temperature. As indicating therange within which such alloy may be worked with satisfactory results, Ishould state that 100 above and below the preferred temperature justindicated constitute the limits, 2', e. such satisfactory workingtemperature lies between 500 and 700 F. This range of temperature,furthcrmore, would appear to apply to any light metal alloy within thegeneral class comprising from 80 per cent upward of magnesium The resultof forging such alloy under the temperature conditions stated is toproduce a much more finely grained structure; also to render the alloymore brittle. However, the tensile strength is very considerablyincreased, and the brittleness may be partially overcome by subsequentheat treatment or annealing, without materially reducing the tensilestrength thus secured. As a result of my improved method of treatingsuch light metal alloys, the latter are rendered adaptable for use in agreat variety of ways for which such alloy is not suitable in the formof castings, whether sand cast or die cast and whether such castings besubsequently heat treated or not. Thus, for example, connecting rods forinternal combustion engines, and other machine parts, where lightnesscombined with great tensile strength is a desirable achievement, may bemade.

Other modes of applying the principle of my invention may be employedinstead of the one explained, change being made as regards the methodherein disclosed, provided the step or steps stated by any of thefollowing claims or the equivalent of such stated ste or steps beemployed.

I there ore particularly point out and distinctly claim as myinvention 1. The method of treating a light metal alloy in whichmagnesium is the predominant constituent, which consists in heating thesame to a temperature of from 500 to 7 00 F., and then forging orsimilarly Working the same.

2. The method of treating a light metal alloy in which magnesium is thepredominant constituent, which consists in heating the same to atemperature of from 500 to 700 F., and then forging the same with swagesor dies heated to approximately the same temperature.

3. The method of treating a magnesiumaluminum alloy in which themagnesium constitutes at least 80% of the total, which consists inheating the same to a temperature of from 500 to 7 00 F and then forgingor similarly working the same.

4. The method of treating a magnesiumaluminum alloy in which themagnesium constitutes at least 80% of the total, Which consists inheating the same to a temperature of from 500 to 700 F., and thenforging or similarly working the same with swages or dies heated toapproximately the same temperature.

5. The method of treating a magnesiumaluminum alloy in which themagnesium constitutes at least 80% of the total, which consists inheating the same to approximately 600 F., and then forging or similarlyworking the same.

6. The method of treating an alloy consisting of approximately 91.5%magnesium and 8.5% aluminum, which consists in heating the same toapproximately 600 F and then forging or similarly working the same.

7. The method of treating an alloy consisting of approximately 91.5%magnesium and 8.5% aluminum, which consists in heating the same toapproximately 600 F., and then forging the same with swages or diesheated to approximately the same temperature.

2Signed by me this 19th day of January, 19 0.

WILLIAM R. VEAZEY.

